1. Field of the Invention
The present invention relates to a method and apparatus for rotating a color image by 90.degree. and, in particular, an efficient method for rotating a color image by 90.degree. using temporary files.
2. Description of the Related Art
Color image editing systems typically include a scanner and a computer system which is equipped with document viewing and editing applications for storing and editing inputted document images. Typically, once an image is scanned in, the operator views the image on the display of the computer system and, if necessary, can edit the image by adjusting color, tone, size, image attributes, rotation, etc. Paint Shop.RTM. and Microsoft Paint.RTM. are examples of these document image editing applications. Once the image has been edited by the operator, a final version of the image can be output using a printer or the like.
Due to the advances in computer technology and printing technology, color image editing systems are being used more and more on desktop computers. However, because desktop computers tend to have limited memory space, image editing and, in particular, color image editing, which uses a large amount of memory space, increases system processing time due to the amount of file-swapping and memory required. This is particularly troublesome when attempting to rotate a color image by 90.degree.. In this regard, to rotate an image by 90.degree., a color image is conventionally randomly accessed by loading an entire image into a memory such that random access of each pixel can be possible. However, as the image size becomes larger and/or resolution becomes higher, this conventional method does not work efficiently or work at all with limited memory resources.
Attempts have been made to resolve the foregoing problem by using file-swapping methods. However, these methods are disadvantageous in the case when the memory size required to load an entire image into memory is bigger than half the size of the available memory due to an extremely large number of file-swappings which must occur. As a result, the processing time grows exponentially as the image size increases.